Boat Lift

ABSTRACT

A boat lift for raising boats out of the water to facilitate maintenance and to reduce corrosion and contamination. The boat lift includes two or more boat lift assemblies positioned and spaced apart so that each boat lift assembly lifts approximately the same fraction of the overall weight of the boat. Each boat lift assembly has a lifting structure with bunk cushions mounted on pivoting bunk bases to prevent damage to the boat hull when lifting. Hydraulic lift mechanisms are enclosed within each boat lift assembly providing a cleaner appearance as well as protection against corrosion and fouling. A dual-pulley mechanism enables lifting distances substantially larger than the length of the lift mechanism. A hydraulic control system ensures that all the boat lift assemblies move up and down simultaneously and at the same rate, thereby maintaining the boat horizontal at all lifting positions.

RELATED APPLICATIONS

The present application claims priority from U.S. Prov. Pat. No. 62/857,711, filed Jun. 5, 2019.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to systems for lifting boats out of the water to facilitate maintenance and to reduce corrosion and contamination.

BACKGROUND OF THE INVENTION

Boat maintenance, cleaning, repairs and/or storage may be facilitated by raising the boat out of the water, typically using a boat lift. Thus, boat lifts are now widely used. However, these boat lifts may be visually unattractive at the pier, as well as presenting dangers to both equipment and personnel when a boat has been raised from the water and is suspended on cables with a danger of unwanted swinging motions.

Often, boat lifts have employed cable lifting mechanisms which are essentially overhead cranes. For stability, there are typically at least two or more of these hoisting mechanisms spaced along the length of the boat to enable more even lifting of the hull and to avoid undue bending stresses as the boat emerges from the water and buoyancy is reduced. However, suspending the boat from hanging cables presents difficulties in an outdoor environment since wind forces on the boat may induce swinging which can be hazardous to both the boat and personnel. During lifting or lowering, while the boat is partially out of the water, wave forces present additional opportunities for unwanted boat motions possibly leading to hull damage and/or personnel injuries. In addition to these operational disadvantages, a group of overhead cranes arrayed along the length of a pier clearly will present an unattractive appearance.

Thus, it would be advantageous to configure a boat lift which may raise a boat uniformly with minimal stresses to the hull during lifting, while avoiding environmental effects such as wind and wave forces during lifting and lowering, as well as when the boat has been fully lifted out of the water for maintenance, cleaning, repairs and/or storage.

It would also be advantageous to configure a boat lift with an improved visual appearance at the pier while maintaining these desirable operational improvements.

SUMMARY OF THE INVENTION

An object of the invention is to provide a lifting system for a boat. The lifting system is designed with improved stability for the boat when it is lifted out of the water, as well as a more attractive visual profile for the lifting assembly.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more thorough understanding of the present invention, and advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1 shows an isometric view of a boat floating above a boat lift with three boat lift assemblies in a lowest position.

FIG. 2 shows an isometric view of a boat ready for lifting by the boat lift of FIG. 1.

FIG. 3 shows an isometric view of the boat lift of FIG. 1 at a highest position with no boat.

FIG. 4 shows an isometric view of a boat lift supported by counterweights.

FIG. 5 shows a side view of a boat lift assembly with a vertical lift beam.

FIG. 6 shows a top isometric view of the boat lift assembly from FIG. 5.

FIG. 7 shows a bottom isometric view of the boat lift assembly from FIG. 5.

FIG. 8 shows a side view of boat lift assembly with a tilted lift beam.

FIG. 9 shows a close-up side view of a bottom foot assembly with a vertical lift beam.

FIG. 10 shows a close-up side view of a bottom foot assembly with a tilted lift beam.

FIG. 11 shows a close-up top isometric view of a portion of the boat lift assembly from FIGS. 5-7.

FIG. 12 shows a close-up bottom isometric view of the boat lift assembly from FIGS. 5-7.

FIG. 13 shows a close-up side isometric view of the boat lift assembly from FIGS. 5-7.

FIG. 14 shows a close-up cutaway side view of the boat lift assembly from FIGS. 5-7.

FIG. 15 shows a side view of a carriage channel assembly configured for a vertical lift beam.

FIG. 16 shows a side view of the carriage channel assembly of FIG. 15 configured for a tilted lift beam.

FIG. 17 shows an isometric cutaway view of a lift beam actuator assembly.

FIG. 18 shows a side cross-sectional view of the lift beam actuator of FIG. 17 fully extended.

FIG. 19 shows a side cross-sectional view of the lift beam actuator of FIG. 17 partially extended.

FIG. 20 shows a side cross-sectional view of the lift beam actuator of FIG. 17 fully retracted.

FIG. 21 shows an isometric view of the lift beam actuator of FIG. 17 with cabling.

FIG. 22 shows an isometric view of the lift beam actuator of FIG. 17 without cabling.

FIG. 23 shows an isometric view of cabling with button cable ends.

FIG. 24 shows an isometric view of cabling with a loop.

FIG. 25 shows a close-up isometric view of a portion of FIG. 24.

FIG. 26 shows a close-up isometric view of a portion of FIG. 21.

FIG. 27 shows an isometric exploded view of a fixed pulley assembly.

FIG. 28 shows an isometric exploded view of the fixed pulley assembly of FIG. 27 with the cable loop in a slot.

FIG. 29 shows a side cross-sectional view of a top of a lift beam.

FIG. 30 shows a side view of the top of the lift beam.

FIG. 31 shows a schematic diagram of a hydraulic control system for a boat lift.

DETAILED DESCRIPTION OF EMBODIMENTS Exemplary Boat Lift Installations

Various embodiments of the invention provide different advantages over the prior art. Not all embodiments provide all the advantages made possible by the invention.

Some embodiments provide multiple lifting structures for raising and lowering a boat. Embodiments can be adapted to particular application by using any desired number of lifting structures and positioning the lifting structure at different positions to provide the desired support for a particular size and boat design. For example, a light boat may use only two lifting structure, while a heavy boat may use 3, 4, or more lifting structures, and the lifting structure may be closer together under the heavier portions of the boat. The lifting structures are preferably arranged with a center lifting structure at the center of gravity of the boat, with additional lifting structures proportionally placed toward the transom and the bow to keep the boat balanced as it is raised and lowered. Each lifting structure, in one embodiment, can lift about 3,500 pounds. A jet ski lift can use a single lifting structure. In some embodiments, the lifting structures are standardized, and additional lifting structures are added for heavier boats. In other embodiments, each of the lifting structures themselves can be designed for an appropriate load, for example, by using thicker structural components, heavier cabling, and higher capacity hydraulics for heavy boats, or thinner structural components, lighter cabling, and lower capacity hydraulics for lighter boats. That is, a boat lift can be readily customized by changing the capacity and/or the number of lifting structures.

Each lifting structures is preferably supported by, and move up and down on, a lifting beam. The lifting beam is preferably stationary. The top of each lifting beams can be attached, directly or indirectly, at a pier. The bottom of each lifting beam can be supported on the bottom of the water on a submerged footing or can be supported on the side of the pier, depending on the pier structure. If supported on a submerged footing, the lifting beam is typically oriented at an acute angle to the pier. Different lifting beams of the same boat lift may be supported differently. The same lifting beam can be oriented vertically and attached to the side of the pier or slanted and supported by a submerged footing. The design of the lifting beam does not need to be modified for different support methods, thereby standardizing components and providing flexibility in adapting the boat lift to different piers. The boat lift does not rely on vertical posts extending above the water line as part of its lifting and support mechanism, although an optional guide post may extend above the water when a boat is lifted.

The lifting structure is supported on only one side by the lifting beam, that is, the lifting structure is a cantilevered out from the lifting beam. The cantilevered design eliminates the requirement for providing a dock, footing, or other means to anchor the lifting structure on the opposing side of the slip space. This design reduces cost, eases installation, and provides a cleaner-looking boat lift.

By using standardized lifting structures and varying the number of lifting structures and the method of support of the lifting beam (e.g., bottom supported or attached to the side of the pier), the boat lift can be adapted to different sized boats and different pier structures using standardized components. An optional dampener, i.e., shock absorbers, such as springs or pneumatic cylinders, acting as wave attenuators, may be attached to the lifting cables to reduce the forces on the boat lift and on the boat being lifted due to waves and wind.

In some embodiments, cables are used to transfer the mechanical force to lift a boat and the cables are attached to the wave attenuators. Some embodiments use two cables in each lifting assembly, the two cables reduce the required cable thickness and provide redundancy in case one of the cables breaks. In some embodiments, the cables are retracted to lift the boat by a hydraulic cylinder in each of the lift beams. Using a common hydraulic pump to pressurize all of the lift beams facilitates in the boat lift facilitates moving all the lift beams in unison to keep the boat level as it is being lifted. A flow divider is preferably used to ensure equally proportion flow to raise each of the lift assemblies uniformly and keep the boat level as it is being raised. Mechanical flow dividers are preferred as they are more accurate.

Positioning the hydraulic pistons inside the lifting beams keeps the hydraulic mechanism out of sight and reduces the visibility of the boat lift, improving aesthetics. Nothing is exposed and the system provides a lower profile compared to prior art lifts that include winches on top of the I-beams. The lift beam may be sealed to keep the interior with the hydraulic cylinder dry or immersed in oil, or the interior of the lift beam may be exposed to the water. The hydraulic lift assemblies could alternatively be located in or on the lifting beams.

In some embodiments, each lifting beam is connected to a top beam supported by the surface of the pier. The top beams spread the weight of the boat and boat lift over a broad area of the pier, reducing the dependence on connecters screwed into the pier to support the weight of the boat and boat lift. A pier counterweight may be attached to the top beam on the side opposite of the lift beam to counter the weight of the boat as it is lifted out of the water. For example, the pier counterweight may hang below surface of the pier from the top beam on the opposite side of the pier from the The combination of a top beam supported on the surface of the pier and the lifting beam, connected to the top beam and supported on the side of the pier or on the bottom of the water, provides a novel support method that allows much of the boat lift to be invisible when a boat is not being lifted.

As use herein, “pier” refers to any platform adjacent to, or extending in to, a body of water and used as a landing stage for boats.

FIGS. 1-3 illustrate a first exemplary boat lift in various operating positions.

FIG. 1 shows an isometric view of a boat lift 100 in a lowest position with a boat 108 still afloat, not yet being lifted by the boat lift—a waterline 120 along a pier wall 102 is shown. In this example, boat lift 100 is configured with three boat lift assemblies: a forward boat lift assembly 110, a center boat lift assembly 112, and a rear boat lift assembly 114. The spacings and positions of the three boat lift assemblies 110, 112, and 114 typically may be set to distribute the weight of boat 108 approximately equally among the three boat lift assemblies 110, 112, and 114. Other embodiments may comprise two boat lift assemblies (typically for shorter or lighter boats), or four or more boat lift assemblies (typically for longer or heavier boats). The number of boat lift assemblies may also depend on the lifting capacity of each of the boat lift assemblies (determined by the detailed design of the boat lift assemblies) as well as the mechanical strength of the hull of boat 108 (determining how far apart the boat lift assemblies may be spaced). The design and operation of the boat lift assemblies are further discussed with regard to FIGS. 5-30. Portions of boat lift assemblies 110, 112, and 114 may extend horizontally underneath a pier deck grating 106, supported by a pier decking 104. In some embodiments, portions of boat lift assemblies may be attached to the pier deck grating 106 and/or to the pier decking 104. Each boat lift assembly is configured with a lifting structure 116 which is vertically-movable (compare with FIGS. 2 and 3). The lifting structures 116 are configured to provide a non-abrasive contact with, and support for, the hull of boat 108, enabling lifting without damage to hull surfaces.

FIG. 2 shows an isometric view of boat 108 ready for lifting by boat lift 100. The lifting structures 116 of each of the three boat lift assemblies 110, 112, and 114 have moved upwards to come into contact with the hull of boat 108. The upward motion of lifting structures 116 is regulated by a common hydraulic control system (not shown) which ensures that the boat is lifted uniformly out of the water.

FIG. 3 shows an isometric view of boat lift 100 of at a highest position with boat 108 (not shown) having been removed. The three lifting structures 116 have moved to the upper limits of their vertical travel ranges. Typically, after boat 108 has been removed from the boat lift, the three lifting structures 116 may be lowered again into the water to present a more attractive visual appearance of the pier. Alternatively, the three lifting structures 116 may remain in the positions illustrated in FIG. 3 until boat 108 is again loaded into the boat lift for lowering back into the water.

FIG. 4 shows an isometric view of a second exemplary boat lift 400 supported by submerged footing 416 where a boat 408 has been raised above a water level 420 by three boat lift assemblies: a forward boat lift assembly 410, a center boat lift assembly 412, and a rear boat lift assembly 414. The same considerations for placement and the number of boat lift assemblies apply here as for FIGS. 1-3. In some cases, a pier wall 402 may be sloped or unsuitable structurally for mounting and supporting the lower ends of the boat lift assemblies (as shown in FIGS. 1-3). In these cases, submerged footing 416 may be used to support the lower ends of boat lift assemblies 410, 412, and 414, as shown. Portions of boat lift assemblies 410, 412, and 414 may extend horizontally underneath a pier deck grating 406, supported by a pier decking 404. In some embodiments, portions of boat lift assemblies may be attached to the pier deck grating 406 and/or to the pier decking 404. Note that the boat lift assemblies 410, 412 and 414 may be the same design as in FIGS. 1-3 since some embodiments of the boat lift enable various mounting configurations for the boat lift assemblies.

Boat Lift Assembly Having a Vertical Lift Beam

FIGS. 5-7 show three views of a boat lift assembly 500 as illustrated in FIGS. 1-3.

FIG. 5 shows a side view of boat lift assembly 500 having a lift beam 510 oriented vertically, as could be the case in a boat lift installation where a pier wall 524 is also approximately vertical and has mechanical integrity suitable to support a lower end of the lift beam 510 as shown. Lift beam 510 is preferably includes an enclosed portion. For example, lift beam 510 could be a hollow square or rectangular beam, or an H-beam having an enclosed, hollow center portion. A hydraulic mechanism is preferably positioned inside the hollow portion of the beam.

Lifting structure 116 comprises a plurality (four shown) of bunk cushions 506 which contact the hull of a boat being lifted when the lifting structure is moved vertically upwards (compare FIG. 1 with FIG. 2). Bunk cushions 506 are attached to bunk pivots 508, which are pivotally-supported by bunk pivot pins 509 on bunk bases 526, wherein the pivoting support enables bunk pivots 508 to accommodate the local shape of the hull of the boat being lifted at the location of each boat lift assembly. This allows stresses on the hull to be equalized as the boat is lifted out of the water and no longer has buoyant support. In the embodiment shown, two bunk cushions 506 are shown on each bunk pivot 508, however in some embodiments other numbers of bunk cushions 506 on each bunk pivot 508 are possible. In some embodiments, other numbers of bunk pivots 508 are also possible. Bunk bases 526 are mounted on a horizontal carriage channel 516 which is capable of vertical motion along lift beam 510. Carriage channel 516 is cantilevered out from the lift beam 510. Because carriage channel 516 is cantilevered, there are two cables coming out of the same side, providing a redundant support. The cantilever design allows the carriage channel to be supported on only one side, eliminating the requirement for providing a dock, footing, or other means to anchor the carriage channel on the opposing side. This design reduces cost, eases installation, and provides a cleaner-looking boat lift.

A lower end of lift beam 510 may be attached to pier wall 524 by a bottom foot assembly 513 comprising: a bottom foot beam bracket 520 pivotally-connected by a bottom foot pivot 522 to a stationary bracket 512 (see FIG. 9). An upper end of lift beam 510 may be attached to an end of a top beam 502, wherein another end of top beam 502 may be supported by a submerged footing 504. As illustrated in FIGS. 1-4, top beams 502 of the boat lift assemblies in a boat lift (e.g., assemblies 110, 112, and 114 in FIGS. 1-3 or assemblies 410, 412, and 414 in FIG. 4) may be covered by a pier deck grating (such as grating 106 in FIGS. 1-3 or grating 406 in FIG. 4), and may be on top of pier decking (such as decking 104 in FIGS. 1-3 or decking 404 in FIG. 4). In some embodiments, top beams 502 may be attached to the pier deck grating and/or to the pier decking.

Vertical motion of carriage channel 516 along lift beam 510 is supported and guided by an upper roller assembly 534 and a lower roller assembly 532. Each of the roller assemblies 532 and 534 may comprise one or more rollers (see FIGS. 11-14, with three rollers pre assembly shown in this embodiment). Upper roller assembly 534 is pivotally-mounted using an upper pivot pin 538 onto ends of both carriage channel 516 and a carriage strap 536 as shown. Lower roller assembly 532 is pivotally-mounted using a lower pivot pin 540 to ends of carriage strap 536 and outer beam extension 518 as shown. Because the carriage channel 516 is cantilevered out from the lift beam 510, the downward force of the weight of carriage channel 516, the bunks, and the boat being lifted, will apply a torque around an axis at lift beam 510 and perpendicular to both carriage channel 516 and to lift beam 510. The torque will be balanced by lower roller assembly 532 pressing against the lift beam 510 on the same side of the lift beam as the bunk, and upper roller assembly 534 pressing into lifting beam 510 on the opposite side of the lift beam from the bunk, to keep carriage channel 516 substantially perpendicular to lift beam 510.

A beam extension assembly 548 comprising an inner beam extension 546 telescoping into, and rigidly attached to, an outer beam extension 518, provides support for carriage channel 516 (see FIGS. 15 and 16). Carriage strap 536 connects between lower roller assembly 532 and upper roller assembly 534. An end of carriage channel 516 is attached to upper roller assembly 534. Carriage channel 516, carriage strap 536, and beam extension assembly 548 form a rigid triangular structure as shown in FIGS. 5-7 and in more detail in FIGS. 15 and 16—this structure provides the mechanical strength and stability to support the weight of the portion of the boat being lifted by each boat lift assembly. Guide post 514 positions the boat to fit into the cradle structure created by the multiple bunk cushions 506 as the lifting structure 116 moves up to contact the hull of the boat (the change in position from FIG. 1 to FIG. 2). In some embodiments, lift post 514 may be replaced by bumpers (not shown) to provide a less obtrusive appearance. Lifting cables 528 connect through a wave attenuating spring mechanism to raise and lower carriage channel 516 (see FIG. 14).

FIG. 6 shows a top isometric view of boat lift assembly 500. Details of the bunk cushions 506 and bunk pivots 508 may be seen more clearly here.

FIG. 7 shows a bottom isometric view of boat lift assembly 500. Details of the beam extension assembly 548 and lower roller assembly 532 may be seen more clearly here.

Boat Lift Assembly Having a Tilted Lift Beam

FIG. 8 shows a side view of a boat lift assembly 800 with lift beam 510 installed in a tilted orientation and supported by a submerged footing 826, instead of being mounted on the pier wall as in FIGS. 5-7. For boat lifts according to some embodiments, this configuration may be preferred due to irregularities of the pier wall, or lack of sufficient mechanical integrity in the pier wall surface to enable mounting onto the pier wall as in FIGS. 5-7. Note that the depicted configuration boat lift installation may, in some embodiments, be achieved with a reconfiguration of the same embodiment as shown in FIGS. 5-7, thus the majority of callouts are unchanged from FIGS. 5-7. A difference between the installations in FIGS. 5-7 and in FIG. 8 is the orientation of the lift beam 510. In order to maintain the horizontal orientation of the carriage channel 516, some adjustments are necessary as illustrated in FIG. 15 (vertical lift beam 510) and FIG. 16 (tilted lift beam 510). The only structural differences between the installation in FIG. 5-7 and the installation in FIG. 8 is the pier and the bottom support for the boat lift assembly—this illustrates that some embodiments may be installed and operated in a range of pier environments. The lower end of the lift beam 510 may be attached to submerged footing 826 by a bottom foot assembly 813 comprising: bottom foot beam bracket 520 pivotally-connected by bottom foot pivot 522 to a pier bracket 824 which is attached to submerged footing 826 (see FIG. 10). The upper end of lift beam 510 is attached to the top beam 502. The upper and lower mounting connections of beam 510 enable the moving carriage to capture the beam, thereby increasing the lifting strength (see FIG. 14).

Alternative Bottom Foot Assemblies

FIG. 9 shows a close-up side view of bottom foot assembly 513 with a vertical lift beam 510, as in FIGS. 5-7. To allow the boat lift assembly to be installed in a variety of alignment conditions with respect to the pier wall 524, the pivoting connection (bottom foot pivot 522) between bottom foot beam bracket 520 and the stationary bracket 512 enables various alignments to be accommodated by pivoting motion between brackets 520 and 512.

FIG. 10 shows a close-up side view of bottom foot assembly 813 with a tilted lift beam 510 (see FIG. 8). Again, as in FIG. 9, the pivoting connection (bottom foot pivot 522) between bottom foot beam bracket 520 and stationary bracket 512 enables various alignments with respect to the pier bracket 824 and submerged footing 826 to be accommodated by pivoting motion between brackets 520 and 512. Note that the same mounting components are applicable to this alternative installation as were used in FIG. 9, and only pier bracket 824 and submerged footing 826 are different.

It should be noted that, in some embodiments, bottom foot assembly 513 (FIG. 9) may be employed with a tilted lift beam 510, as might be the situation where the pier walls are sloped and have sufficient mechanical integrity to support the boat lift assembly. Further, in some embodiments, bottom foot assembly 813 (FIG. 10) may be employed with a vertical lift beam 510, as might be the situation where the pier walls are approximately vertical but have insufficient mechanical integrity to support the boat lift assembly.

Close Up Views of the Carriage Lift Assembly

FIG. 11 shows a close-up top isometric view of a portion of boat lift assembly 500.

FIG. 12 shows a close-up bottom isometric view of a portion of boat lift assembly 500.

FIG. 13 shows a close-up side isometric view of a portion of boat lift assembly 500.

FIG. 14 shows a close-up cutaway side view 1400 of a portion of boat lift assembly 500. Referring to FIGS. 11-14, lower roller assembly 532 comprises one or more lower rollers 1105, three lower rollers in the embodiment shown, each rotating on a lower roller axle 1104. Upper roller assembly 534 comprises one or more upper rollers 1107, three upper rollers in the embodiment shown, each rotating on an upper roller axle 1106. Lifting cable 528 extends down through the center of wave attenuating spring 1402 (FIG. 14), connecting to the bottom end of wave attenuating spring 1402 through wave attenuating spring retainer 1404. The upper end of wave attenuating spring 1402 presses against wave attenuating spring stop 1406 which transfers the upward lifting force through wave attenuating spring housing 530 to the lower end of beam extension assembly 548, which then conveys the lifting force to carriage channel 516. Wave attenuating spring 1402 also cushions the lifting structure (see FIGS. 17-22) against vertical boat motions due to water and wind forces. In some embodiments, wave attenuating spring 1402 may comprise a spring, a rubber tube, a pneumatic cylinder, or other type of wave attenuating spring device.

Carriage Channel Assemblies for Various Lift Beam Orientations

FIGS. 15 and 16 illustrate how a carriage channel assembly 1500, comprising carriage channel 516, carriage strap 536, and beam extension assembly 548 (comprising outer beam extension 518 and inner beam extension 546), may be configured for two installed orientations of lift beam 510. Inner beam extension 546 slides into outer beam extension 518 to form beam extension assembly 548.

FIG. 15 shows a side view of carriage channel assembly 1500 configured for a boat lift installation where lift beam 510 is vertical as in FIGS. 1-3. In this configuration, both the upper roller assembly 534 and the lower roller assembly 532 will also be oriented vertically as shown.

During installation of the boat lift, the horizontal spacing between the roller assemblies 532 and 534 should be set to correspond to the width of lift beam 510 so that lower rollers 1105 and upper rollers 1107 will simultaneously be in contact with opposing walls of lift beam 510. Also, the orientation of carriage channel 516 also must be set during installation to be horizontal (independent of the orientation of lift beam 510). Both of these settings are effected by sliding inner beam extension 546 into outer beam extension 518 a distance which simultaneously configures carriage channel 518 to be horizontal while both upper roller assembly 534 and lower roller assembly 532 may roll along the walls of lift beam 510—once this has been achieved, one or more holes are match-drilled through the wall of outer beam extension 518 (over a portion of outer beam extension 518 which overlaps with inner beam extension 546) and then continues through the wall of inner beam extension 546. Once this hole is drilled, a pin, screw or other fastening means may be inserted through the match-drilled hole to lock-in the distance that inner beam extension 546 extends into outer beam extension 518—this operation sets the length of the beam extension assembly 548. During installation of the boat lift, a carriage shaft 1502 is fitted through a hole in carriage channel 516. Slot 1504 may enable adjustment of the location of carriage shaft 1502 along the length of carriage channel 516.

FIG. 16 shows a side view of carriage channel assembly 1500 set for a boat lift installation where lift beam 510 is tilted as in FIG. 4. All callouts are the same since the same carriage channel assembly 1500 is illustrated here as in FIG. 15—the ability to install the carriage channel assembly 1500 to operate with lift beams 510 mounted at multiple tilt angles is an aspect of some embodiments. When lift beam 510 is tilted, beam extension assembly 548 will be shorter than in FIG. 15—this is effected by inserting inner beam extension 546 farther into outer beam extension 518 before performing the match-drilling operation described above for FIG. 15. The overall set-up and installation method here is the same as for FIG. 15.

Lifting Actuator Assembly

FIGS. 17-22 and their descriptions discuss the design and operation of a lifting actuator assembly 1700 according to an example embodiment. The lifting actuator assembly 1700 is positioned inside each lift beam 510 in the boat lift assemblies and effectuates the raising and lowering of the lifting structures by means of retracting or paying out cable 528, respectively.

FIG. 17 shows an isometric cutaway view of lift beam 510 with a lifting actuator assembly 1700 mounted inside lift beam 510. In some embodiments, the interior of lift beam 510 is sealed at a bottom end to prevent water from entering, wherein an open top end is above the water line. In some embodiments, the interior of lift beam 510 may be sealed at a bottom end and filled with a lubricating fluid to aid in smooth operation of the lifting actuator assembly 1700. In some embodiments, the lift beam 510 may not be sealed. This view does not show the cabling that is wrapped back-and-forth between a fixed pulley 1708 and a moving pulley 1704 (see FIGS. 21, 23, and 24). Fixed pulley 1708 is attached to an end of a hydraulic cylinder 1702 attached to lift beam 510. Moving pulley 1704 is attached to a moving end of a piston rod 1706. Piston rod 1706 is attached to a piston 1710 which slides from one end of hydraulic cylinder 1702 to the other end due to the force applied to an inner surface of piston 1710 by the pressurized hydraulic fluid (not shown) in hydraulic cylinder 1702. A sliding seal 1712 at an end of hydraulic cylinder 1702 opposite from the end where fixed pulley 1708 is attached allows passage of piston rod 1706 while preventing leakage of the pressurized hydraulic fluid. The upper right end of lift beam 510 in FIG. 17 would be the upper end of lift beam 510 in FIG. 5, while the lower left end of lift beam 510 in FIG. 17 would be the lower end of lift beam 510 in FIG. 5. The lower end of lift beam 510 may be sealed to prevent entry of water, and the interior of lift beam 510 may be filled with oil (e.g., food-grade oil), or another fluid to reduce corrosion and improved lubrication of the pulley mechanism. A counterbalance valve 1714 is operable to set up a back-pressure in the control circuit which controls the flow of hydraulic fluid into and out of the cylinder 1702, to ‘counterbalance’ the effects of the load on the cylinder.

Other types of linear actuators may perform the function of hydraulic cylinder 1702 in some embodiments, such as motorized lead-screw actuators, motorized recirculating-ball lead-screw actuators, motorized rack-and-pinion geared actuators, motorized worm-gear actuators, etc. Different numbers of moving pulleys 1704 and fixed pulleys 1708 may be employed in some embodiments—the choice of number of pulleys may be determined by the requirements for how far to raise a boat from the water, as well as the weight to be raised by each boat lift assembly and the drive capacity of the linear actuator.

FIGS. 18-20 show side cross-sectional views of lifting actuator assembly 1700 in three positions: fully extended (FIG. 18), partially extended (FIG. 19), and fully retracted (FIG. 20)—in FIGS. 5-8, the left sides of FIGS. 18-20 would be at the bottoms of lift beams 510 and the right sides of FIGS. 18-20 would be at the tops of lift beams 510. Progressing from FIG. 20 through FIG. 19 to FIG. 18, piston 1710 and piston rod 1706 are pushed to the left by the pressurized hydraulic fluid in hydraulic cylinder 1702, thereby causing moving pulley 1704 to move to the left, farther away from fixed pulley 1708. As the pulleys 1704 and 1708 move farther apart, the cabling (see FIGS. 21, 23, and 24) rotates around the pulleys, causing lifting cables 528 to be retracted, thereby pulling lifting structure 116 upwards along lift beam 510.

FIG. 21 shows an isometric view of lifting actuator assembly 1700 with cabling. Fixed pulley 1708 is mounted within a fixed pulley block 2106 (see FIGS. 26-28). Moving pulley 1704 is mounted within a moving pulley block 2104, which is attached to an outer end (i.e., the end outside of hydraulic cylinder 1702) of piston rod 1706. Cables 2012 wind back-and-forth between moving pulley 1704 and fixed pulley 1708. Lifting cables 528 extend out from pulley 1708 as shown—the weight of lifting structure 116, as well as the weight of a portion of the boat being lifted, tend to pull upwards on lifting cables 528 in FIG. 21 (because an additional pulley reverses the cable direction—see FIG. 29), which in turn applies a force upon moving pulley 1704 tending to push piston rod upwards (i.e., into hydraulic cylinder 1702). When pressurized hydraulic fluid (not shown) is admitted into hydraulic cylinder 1702, pressure is exerted against piston 1710, causing piston rod 1706 to move downwards in FIG. 21 (going from the configuration illustrated in FIG. 20 towards that in FIG. 18), thereby lowering moving pulley 1704. Thus, lifting cable 528 will be pulled downwards in FIG. 21. Note that the distance that lifting cable 528 is retracted will be larger than the distance that moving pulley 1704 moves downwards—if there are N cable lengths 2102 between fixed pulley 1708 and moving pulley 1704, then the retraction length of lifting cables 528 (i.e., the distance that lifting structure 116 will be pulled upwards) will be N times the travel distance of moving pulley 1704, however the pulling force of lifting cables 528 on lifting structure 116 will be reduced at least by 1/N (typically to less than 1/N due to friction).

FIG. 22 shows an isometric view of lifting actuator assembly 1700 without cabling for clarity—piston rod 1706 is shown partially extended through sliding seal 1712.

Lifting Actuator Assembly Cabling

FIG. 23 shows an isometric view of an embodiment of cabling 2300 corresponding to FIG. 21, but not showing any of the mechanical components. There are two separate cables, each cable having cable loops 2302 around the pulleys (not shown), with cable portions extending back-and-forth between fixed pulley 1708 and moving pulley 1704 (not shown)—each cable is terminated with a button cable end 2304. In this illustration, each of the two cables 2102 has four lengths 2102 between fixed pulley 1708 and moving pulley 1704 (corresponding to loops 2302), thus N=4 (see FIG. 21), thus the retraction ratio for lifting cables 528 will be four times the distance that moving pulley 1704 travels downwards. This travel gain factor enables some embodiments to pull a lifting structure 116 a substantial upward distance with a relatively shorter lifting actuator assembly 1700.

FIG. 24 shows an isometric view of an alternative embodiment, relative to FIG. 23, of cabling 2400, wherein instead of two separate cables as in cabling 2300, here a single cable is used (i.e. lifting cables 528 are the two ends of the same cable). A loop 2402 is clamped within support plate 2702 (see FIG. 27). Operation of the lifting actuator assembly is the same as in FIG. 23.

FIG. 25 shows a close-up isometric view of an upper portion of cabling 2400.

FIG. 26 shows a close-up isometric view of an upper portion of lifting actuator assembly 1700. Fixed pulley 1708 is supported by a fixed pulley axle 2602 which extends between the two sides of fixed pulley block 2106. For added mechanical strength, a cylinder end plate 2606, typically made from a strong material such as steel, may function to spread the force exerted by hydraulic cylinder 1702 across the entire base of fixed pulley block 2106, which thus may be made from a lighter material such as aluminum. Pressurized hydraulic fluid may be introduced into hydraulic cylinder 1702 through hydraulic fluid connections 2610 in a cylinder hydraulic connections block 2608. The use of two redundant lifting cables 528 provides improved reliability and safety.

Fixed Pulley Assembly

FIG. 27 shows an isometric exploded view of the fixed pulley end of lifting actuator assembly 1700. A slot 2702 in cylinder end plate 2606 is configured to clamp cable end loop 2402 when fixed pulley block 2106 is attached to cylinder end plate 2606 using a pulley block connector 2704.

FIG. 28 shows an isometric exploded view 2800 of the fixed pulley end of lifting actuator assembly 1700 with cable loop 2402 inserted into slot 2702. The depth of slot 2702 may be slightly smaller than the cable diameter in loop 2402 so that when fixed pulley block 2106 is attached to cylinder end plate 2606 by pulley block connector 2704, then loop 2402 is clamped tightly, preventing motion of the cable.

Details of the Top of the Lift Beam

FIG. 29 shows a side cross-sectional view of a top portion of boat lift assembly 500. An upper pulley 2904 is mounted on an upper pulley axle 2902. A short section of cable 2906 extends between fixed pulley 1708 and upper pulley 2904. The function of upper pulley 2904 is to change the direction of the cable emerging upwards from the lifting actuator assembly to extend downwards towards lifting structure 116 (see FIG. 14). A wiping brush 2910 is operable to wipe water off cable 528 as it moves upwards towards upper pulley 2904. Cable section 2906 passes through a wiping seal 2908 to further remove water from cable 2906 as it is moving through the wiping seal 2908.

FIG. 30 shows a side view of a top portion of boat lift assembly 500.

Exemplary Boat Lift Hydraulic Control System

FIG. 31 shows a schematic diagram of an exemplary hydraulic control system 3100 for a boat lift. A control computer 3102 may be configured with a display screen 3104 to present to an operator various options for controlling the status and operation of a boat lift, as in FIGS. 1-4, for example. Instructions for controlling the boat lift may be stored in a non-volatile computer-readable storage medium 3106, which may be configured as a hard-disk drive, a flash memory, or other type of computer data storage device. Communication between the non-volatile computer-readable storage medium 3106 and the computer 3102 may be through a link 3108 which may be hard-wired or wireless. Computer 3102 may be a desktop computer, a laptop computer, a tablet computer, or another type of computing device capable of executing instructions stored in storage medium 3106. Computer 3102 communicates with a hydraulic controller 3110 through a link 3112, which may be hard-wired or wireless. Hydraulic controller 3110 is typically configured with individual hydraulic feed lines to hydraulic cylinders in each lifting assembly of the boat lift. In the example shown here, corresponding to the boat lift in FIGS. 1-4, there are three lifting assemblies: front lift assembly 3114, center lift assembly 3118 and rear lift assembly 3122. Front lift assembly 3114 is activated by a front hydraulic line 3116 from hydraulic controller 3110. Similarly, center lift assembly 3118 is activated by a center hydraulic line 3120, and rear lift assembly 3122 is activated by a rear hydraulic line 3124.

In some embodiments, hydraulic lines 3116, 3120, and 3124, may be single bi-directional hydraulic lines in which the pressurized hydraulic fluid may flow out from hydraulic controller 3110 to the lifting assembly to cause upward (lifting) motion, and the pressurized hydraulic fluid may also flow back to hydraulic controller 3110 from the lifting assembly during downward (lowering) motion. In some embodiments, lines 3116, 3120, and 3124 may comprise multiple hydraulic lines, wherein at least one line may enable pressurized hydraulic fluid to flow from hydraulic controller 3110 to the lifting assembly (during lifting), while one or more lines may enable pressurized hydraulic fluid to flow from the lifting assembly back to the hydraulic controller 3110 (during lowering).

Hydraulic controller 3110, operating under control of computer 3102 through commands conveyed over link 3112, may control each of the lifting assemblies 3114, 3118 and 3122 individually to ensure that the boat lift will lift and lower a boat uniformly and smoothly, to avoid undesirable tilting or bending of the boat as it is raised out of the water and an increasing fraction of the weight of the boat falls on the lifting assemblies as buoyant support decreases.

The following are additional example embodiments according to the present disclosure:

A first embodiment, which is a boat lift, comprising multiple boat lift assemblies, at least one boat lift assembly including a lift beam; a lifting structure configured to move along the lift beam; and a lifting actuator assembly, located inside the lift beam and configured to move the lifting structure.

A second embodiment, which is the boat lift of the first embodiment, wherein the boat lift assembly further comprises a top beam; and a pier counterweight; wherein a first end of the top beam is attached to an upper end of the lift beam, and wherein a second end of the top beam is attached to the pier counterweight.

A third embodiment, which is the boat lift of the first embodiment, wherein in the boat lift assembly, the lifting structure further comprises a bunk pivot; and a bunk cushion attached to the bunk pivot.

A fourth embodiment, which is the boat lift of the third embodiment, wherein in the boat lift assembly, the lifting structure further comprises a carriage channel; and a bunk base; wherein the bunk base is attached to the carriage channel, and wherein the bunk pivot is pivotally attached to the bunk base.

A fifth embodiment, which is the boat lift of the first embodiment, wherein in the boat lift assembly, the lifting structure further comprises a guide post.

A sixth embodiment, which is the boat lift of the first embodiment, wherein in the boat lift assembly, a lower end of the lift beam is configured to be mounted on a wall of a pier.

A seventh embodiment, which is the boat lift of the first embodiment, wherein the boat lift assembly further comprises a submerged footing, and wherein a lower end of the lift beam is configured to be mounted on the submerged footing.

An eighth embodiment, which is the boat lift of the first embodiment, wherein in the boat lift assembly, the lifting actuator assembly further comprises a hydraulic cylinder, having a first end attached at an end of the lift beam; a fixed pulley, attached at the first end of the hydraulic cylinder; a piston rod; a piston, inside the hydraulic cylinder, and attached to a first end of the piston rod; a moving pulley attached to a second end of the piston rod; and a cable routed between the fixed pulley and the moving pulley; wherein an end of the cable protrudes from the lifting actuator assembly, and wherein motion of the moving pulley away from the fixed pulley causes the protruding end of the cable to be retracted into the lifting actuator assembly.

A ninth embodiment, which is the boat lift of the eighth embodiment, wherein in the boat lift assembly, the retraction of the cable into the lifting actuator assembly raises the lifting structure.

A tenth embodiment, which is the boat lift of the eighth embodiment, further comprising a control computer; a hydraulic control system, configured with a hydraulic line to at least one boat lift assembly; a connection between the control computer and the hydraulic control system, the connection being configured to send commands from the control computer to the hydraulic control system; a non-volatile computer-readable storage medium, configured to store instructions to be executed by the control computer; and a connection between the control computer and the non-volatile computer-readable storage medium, the connection being configured to relay computer instructions to the control computer.

An eleventh embodiment, which is a boat lift assembly, comprising a lift beam; a lifting structure configured to move along the lift beam; and a lifting actuator assembly, located inside the lift beam and configured to move the lifting structure.

A twelfth embodiment, which is the boat lift assembly of the eleventh embodiment, further comprising a top beam; and a pier counterweight; wherein a first end of the top beam is attached to an upper end of the lift beam, and wherein a second end of the top beam is attached to the pier counterweight.

A thirteenth embodiment, which is the boat lift assembly of the eleventh embodiment, wherein the lifting structure further comprises a bunk pivot; and a bunk cushion attached to the bunk pivot.

A fourteenth embodiment, which is the boat lift assembly of thirteenth embodiment, the lifting structure further comprising a carriage channel; and a bunk base; wherein the bunk base is attached to the carriage channel, and the bunk pivot is pivotally attached to the bunk base.

A fifteenth embodiment, which is the boat lift assembly of the eleventh embodiment, the lifting structure further comprising a guide post.

A sixteenth embodiment, which is the boat lift assembly of the eleventh embodiment, wherein a lower end of the lift beam is configured to be mounted on a wall of a pier.

A seventeenth embodiment, which is the boat lift assembly of eleventh embodiment, further comprising a submerged footing, wherein a lower end of the lift beam is configured to be mounted on the submerged footing.

An eighteenth embodiment, which is the boat lift assembly of the eleventh embodiment, the lifting actuator assembly further comprising a hydraulic cylinder, having a first end attached at an end of the lift beam; a fixed pulley, attached at the first end of the hydraulic cylinder; a piston, inside the hydraulic cylinder; a piston rod, attached at a first end to the piston; a moving pulley attached to a second end of the piston rod; and a cable routed between the fixed pulley and the moving pulley; wherein an end of the cable protrudes from the lifting actuator assembly, and wherein motion of the moving pulley away from the fixed pulley causes the protruding end of the cable to be retracted into the lifting actuator assembly.

A nineteenth embodiment, which is the boat lift assembly of the eighteenth embodiment, wherein the retraction of the cable into the lifting actuator assembly raises the lifting structure.

A twentieth embodiment, which is a method for raising and lowering a boat out of and into the water, the method comprising configuring a boat lift to include a multiple boat lift assemblies, each boat lift assembly including a lift beam; a lifting structure configured to move along the lift beam; and a lifting actuator assembly, located inside the lift beam and configured to move the lifting structure; a control computer; a hydraulic control system, configured with a hydraulic line to at least one boat lift assembly; a connection between the control computer and the hydraulic control system, the connection being configured to send commands from the control computer to the hydraulic control system; a non-volatile computer-readable storage medium, configured to store instructions to be executed by the control computer; and a connection between the control computer and the non-volatile computer-readable storage medium, the connection being configured to relay computer instructions to the control computer; loading instructions from the non-volatile computer-readable storage medium into the control computer; executing the instructions in the control computer; sending commands to the hydraulic control system from the control computer; directing hydraulic fluid through the hydraulic lines from the hydraulic control system to each boat lift assembly to activate the lifting actuator assemblies based on the commands from the control computer.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made to the embodiments described herein without departing from the scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification.

As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps. 

1. A boat lift, comprising multiple boat lift assemblies, at least one boat lift assembly including: a lift beam; a lifting structure configured to move along the lift beam; and a lifting actuator assembly, located inside the lift beam and configured to move the lifting structure.
 2. The boat lift of claim 1, wherein the lifting structure extends cantilevered from the lift beam.
 3. The boat lift of claim 1, wherein the boat lift assembly further comprises: a top beam for resting on a pier surface; and a pier counterweight; wherein a first end of the top beam is attached to an upper end of the lift beam, and wherein a second end of the top beam is attached to the pier counterweight.
 4. The boat lift of claim 3 further comprising a pier deck grating over the top beam.
 5. The boat lift of claim 1, wherein in the boat lift assembly, the lifting structure further comprises: a carriage channel; and a bunk base; wherein the bunk base is attached to the carriage channel, and wherein the bunk pivot is pivotally attached to the bunk base.
 6. The boat lift of claim 5 in which the lifting structure further comprises an outer beam extension extending from the carriage channel to the lift beam.
 7. The boat lift of claim 6 further comprising at least one roller connected between the outer beam extension and the lift beam.
 8. The boat lift of claim 7 further comprising at least a second roller connected between the carriage channel and the lift beam.
 9. The boat lift of claim 1, wherein in the boat lift assembly, the lifting structure further comprises a bunk pivot; and a bunk cushion attached to the bunk pivot.
 10. The boat lift of claim 1, wherein in the boat lift assembly, the lifting structure further comprises a guide post.
 11. The boat lift of claim 1, wherein in the boat lift assembly, a lower end of the lift beam is configured to be mounted on a wall of a pier.
 12. The boat lift of claim 1, wherein the boat lift assembly further comprises a submerged footing, and wherein a lower end of the lift beam is configured to be mounted on the submerged footing.
 13. The boat lift of claim 1, further comprising an actual within the lift beam and at least one cable connected to the actuator for raising and lowering the lifting structure.
 14. The boat lift of claim 13, in which the at least one cable comprises two cables.
 15. The boat lift of claim 13, in which the at least one cable is connected to the lifting structure through a damper to attenuate motion due to waves or wind.
 16. The boat lift of claim 1, wherein in the boat lift assembly, the lifting actuator assembly further comprises: an actuator rod; a linear actuator, having a first end attached at an end of the lift beam, and wherein the linear actuator is configured to move the actuator rod linearly along a long axis of the lift beam; a fixed pulley, attached at the first end of the linear actuator; a moving pulley attached to an end of the actuator rod; and a cable routed between the fixed pulley and the moving pulley; wherein an end of the cable protrudes from the lifting actuator assembly, and wherein motion of the moving pulley away from the fixed pulley causes the protruding end of the cable to be retracted into the lifting actuator assembly.
 17. The boat lift of claim 16, wherein the linear actuator comprises a hydraulic cylinder.
 18. The boat lift of claim 16, wherein the linear actuator comprises a motorized lead-screw actuator, a motorized rack-and-pinion geared actuator, or a motorized worm-gear actuator.
 19. The boat lift of claim 16, wherein in the boat lift assembly, the retraction of the cable into the lifting actuator assembly raises the lifting structure.
 20. The boat lift of claim 16, further comprising: a control computer; a hydraulic control system, configured with a hydraulic line to at least one boat lift assembly; a connection between the control computer and the hydraulic control system, the connection being configured to send commands from the control computer to the hydraulic control system; a non-volatile computer-readable storage medium, configured to store instructions to be executed by the control computer; and a connection between the control computer and the non-volatile computer-readable storage medium, the connection being configured to relay computer instructions to the control computer.
 21. The boat lift assembly of claim 1 in which the lift beam is sealed to prevent water from contacting the lifting actuator assembly. 22-36. (canceled) 